Brush holder



April 14, 1925. 11,533,237

" J. v. DOBSON BRUSH HOLDER Filed July 19, 1924 ixr MM? 3 w WM 6 WITNESSES: INVENTOR MM/ JO/m M 006500 ATTORNEY Patented Apr. 14, W25.

OFFICE.

JOHN V. IDO'BSON, F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIG & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

BRUSH HGLDER.

application filed 311137.19, 1924. Serial No. 726,911.

To all? whom it may concern.

Be it known that 1, JOHN V. DoBsoN, a citizen of the United States. and a resident of lVilkinsburg, in the county of Allegheny andState of Pennsylvania, have invented a new and useful Improvement in Brush Holders, of which the following is a specification.

My invention relates to details of construction of brush holders for current-collecting devices of electrical machines.

The principal object of my invention is to provide a cheap, easily assembled and efiicientconstruction for the spring arm or pressure finger of a brush holder, whereby the spring is totally enclosed out of contact with dust, grease or other foreign matter which is carried in the ventilating air, and whereby the pressure finger is provided with a large bearing surface on the supporting shaft or spindle so that deterioration due to current-flow or wear is reduced.

In the accompanying drawing: Figure 1 1s a s1de v1ew. partly in sect1on, showing my improved brush holder;

Fig. 2 is a side view of the pressure finger or spring pressed arm which bears on the top of the brush;

Fig. 3 is a' cross-sectional view on the line IIIIH of Fig. 2, showing the hub of the pressure finger, the spring and the ratchet in place on the shaft; and

Fig. 4 is a side view of the spring.

My invention has been developed primarily for use on single-phase commutator motors for locomotives, although it is applicable, of course, to any brush mechanism of a currentcollecting device. In the drawing, the commutator member of the machine is indicated at 6 and is shown in operative relation to a brush-holder mechanism comprising a supporting bracket 8, a brush box 9, rigidly carried thereby, and a spindle or shaft 10, which is removably mounted on the brush holder, as by means of a washer 11 and cotter pin 12, in spaced relation to the brush box.

Mounted on the shaft is a pressure finger or a spring-pressed arm 13, terminating in an end portion 14:, which bears against the top of the brush 15 and holds the same in operative position against the commutator cylinder. The pressure finger ,13 is provided with an enlarged hub portion 17 which isprovided with an annular recess 18, open at one end and closed at the other,

whereby a helical spring 19 may be inserted and hooked into operative'engagement with a perforation 20 at the inner end of the annular recess 18.

A ratchet 22 is movably mounted on the shaft 10 adjacent the open end of the annular recess 18, and the outer end of the helical springis hooked into a perforation 23 in the ratchet. A pawl 24 is secured to the brush-holder frame for engaging the ratchet 22, whereby the latter may be rotated to place the spring under the required degree of tension. The usual current shunt 26 is provided for carrying current from the pressure finger 13 to the brush-holder frame in order to prevent the passage of current through the spring member.

It will be noted, from the foregoing description, that my invention avoids the necessitv for utilizing spiral springs, that a helical spring is totally enclosed and thus rendered satisfactorily operative in practice. that but few parts are required. thus reducing the cost of manufacture. and that the enlarged hub portion of the pressure finger provides an ample bearing surface between said finger and the shaft whereby diificulties due to the flow of current and the wearing away of the hub member are eflectually eliminated.

I claim as my invention:

1. A brush holder for electrical machines comprising a brush-holder frame having a brush box and a removably mounted shaft, a laterally extending pressure finger extending over the brush box and adapted to engage the top of the brush, said finger having an enlarged hub portion journaled on said shaft, said hub portion having an annular recess open at one end. a helical spring mounted in said recess and having its inner end detachably secured therein, a ratchet wheel freely mounted on said shaft adjacent the open end of said annular recess, means for detachably securing the other end of said spring to said ratchet wheel. and a pawl carried by the brush-holder frame for engaging said ratchet wheel. I

2. A brush holder for electrical machines comprising a brush-holder frame havin a brush box and a shaft, a laterally extending pressure finger extending over the brush box and adapted to engage the top of the brush, said pressure linger having an enlarged hub portion journaled on said shaft, said hub pressure portion having an annular recess open at one end, a helical spring mounted in said recess and having its inner end detachably secured therein. a member mounted on said shaft against the open end of said annular recess for totally enclosing said spring: and retaining the outer end thereof. and means for rotating said member and holding it in a fixed angular position for maintaining said pressure arm under stress.

3. A brush holder for electrical machines comprising a supporting shaft. a finger having a hub portion on said shaft and adapted to yieldably press a brush into ope-rative engagement with a co-operating current-collecting device, said hub portion having an annular recess open at one end, a helical spring mounted in said recess and having its inner end detachably secured therein, a member mounted on said shaft against the open end of said annular recess for totally enclosing said spring and retaining the outer end thereof, and means for rotating said member and holding it in a fixed annular position for maintaining said pressure arm under stress.

In testimony whereof, I have hereunto subscribed my name this 7th day of July,

JOHN V. DOBSON. 

